Heretofore, a one-piece type golf ball has exclusively been used as golf balls used in driving ranges in consideration of its durability. However, there was a problem that the one-piece golf ball was extremely inferior regarding flight performance and the feeling when it was hit in comparison with a golf ball for a round of golf.
Of course, a golfer desires to use the golf ball designed for a round of golf at driving ranges. A thread wound golf ball (a golf ball obtained by winding a thread rubber on a center and covering the resulting thread rubber layer with a cover) is extremely superior with regard to the feeling when it is hit, but is extremely inferior in durability and further is expensive. Therefore, the thread wound golf ball is not suitable as a golf ball used in driving ranges.
Further, the golf ball for a round of golf having a two-piece structure in which a solid core is covered with a cover is too rigid to be hit lots of times and, therefore, normal practice can not be conducted. Therefore, this golf ball is not also suitable for use in driving ranges.
Therefore, a trial has been conducted for softening the core to cushion the shock upon impact. However, even if the core is softened, the durability becomes inferior because the difference in hardness between the cover and the core is large. Therefore, this type of ball is also not suitable for practical use.
As described above, a conventional golf ball for practice is inferior regarding flight performance and the feeling when it is hit in comparison with a golf ball for a round of gold and the type of golf ball for a round is inferior in durability and is too rigid to hit lots of times. Therefore, they are not suitable as golf balls used in driving ranges.